The present invention relates to a recycling automatic document feeder (RADF) for a copier or similar image forming apparatus and, more particularly, to an RADF capable of preventing curled or otherwise deformed documents from being damaged when they are recirculated.
An RADF is generally constructed to transport the lowermost one of documents stacked on a document table to a predetermined document set position on a copier and, after the document has been illuminated by the copier, returns it to the table. To separate the lowermost sheet from the other sheets, air under pressure may be blown against one edge of the stack of documents, as disclosed in Japanese Utility Model Laid-Open Publication No. 127681/1990 by way of example. Specifically, in this type of RADF, a nozzle blows compressed air against the edge of a document stack set on a document table face down. At the same time, a suction tank sucks the lowermost document to retain it on a feed belt, while separating it from the other documents. The RADF has an opening for receiving the documents sequentially returned after illumination. A parting plate is disposed in this opening and presses the documents having not illuminated, thereby separating such documents from the documents returned after illumination.
However, the conventional RADF described above has some problems left unsolved, as follows. Assume that the documents stacked on the document table are noticeably curled. Then, when documents undergone illumination are sequentially returned to the table, the parting plate raised by the underlying curled documents obstructs and damages the returned documents. Moreover, when the parting plate is raised by the underlying curled stack to an excessive level, it loses the expected function and allows the returned documents to run onto the stack. This prevents the returned documents from being distinguished from the non-illuminated documents, i.e., prevents the last document of the non-illuminated stack from being identified. As a result, the RADF fails to transport the documents with accuracy.